Traditionally, for the positioning of a hand-held power tool on a wall, separate measuring components or devices are needed. These can be tachymeters, laser rotators, line lasers, electronic distance meters such as the Leica Disto, or simple analogue metering devices. Nevertheless, in order to save time, it would be advantageous for a craftsman to be able to position a hand-held power tool, for example a power drill, an electric screwdriver or a pneumatic nail gun on a wall without the need of a separate measuring device.
Inside of a room or building for the positioning of a tool on a wall usually it is sufficient to know the distances or the span to the walls on the right and on the left, and those to the floor and to the ceiling. In the conventional case, for example when the room is of cubical form, the wall is rectangular and the adjacent walls, floor and ceiling are perpendicular to this wall. In this case, knowing above mentioned distances would also allow to establish a local coordinate system to position the tool relative to a reference point, e.g. by nulling the coordinates on a distinct location at the wall and deriving relative coordinates in a system with axes parallel to the walls, the floor and the ceiling.
Conventionally, this problem would be solved by mounting distance sensors on the tool that allow measurements to the walls, floor and ceiling in parallel, i.e. those distance sensors mounted perpendicularly. This, however, forces the operator to align the tool in a way that the sensors are aligned exactly perpendicularly to the walls. If there is no indicator such as a vial showing the operator the correct levelling of the instrument, the system has to automatically detect the plumb line direction and align the range sensors accordingly.
Alternatives can be solutions with broadcasters for positioning, such as Nikon's optical indoor positioning system iSite/iGPS or Locata's pseudolite-based positioning system. Those have the disadvantage of being dependent on additional equipment and a complex setup.
There are some documents in prior art that describe distance measurement perpendicular to the tooling direction by devices that are fixedly mounted on the tool and not rotating.
EP 1 275 470 B1 describes a manually guided support for a handheld tool and means for sensing the position of this support.
In DE 20 2004 018 003 U1 a positioning system fixed on a handheld power tool is disclosed that measures distances in two directions, horizontally and vertically, thus determining a position of the tool on a wall.
EP 1 249 291 B1 not only discloses a distance measurement perpendicular to the tooling direction by a device that is fixedly mounted on the tool, it also describes a solution that determines the shortest distance to the floor by a distance measurement that swings around the direction of gravity, the found minimum representing the shortest distance to the floor. This is realized by a freely rotating sensor or deflection means with asymmetrically distributed weight that is oscillating in a scan range. EP 249 291 B1 also discloses the use of an accelerometer sensor to determine the plumb line direction.
The solutions disclosed in these documents all make use of fixed distance measuring sensors, which forces the operator to exactly align the tool for the measurement.
EP 1 517 117 A1 discloses a method and system for determining the spatial position of a hand-held measuring appliance, which is not designed to be placed on a hand-held power tool. For this purpose at least two reference points are needed that are detected by a scanning laser beam. By measuring angles and distances between these reference points and the measuring appliance the actual position of the appliance can be deduced.